About the Swim Pace Calculator
This swim pace calculator converts a swim time and distance into the number every coach and training plan uses: your pace per 100 metres (or per 100 yards in a short-course yard pool). It also shows your speed and projects finish times for common pool and open-water distances, from a 50 sprint to an Ironman 3.8 km swim, if you held the same pace.
It is useful for triathletes planning a race swim, masters and fitness swimmers tracking progress, and anyone setting send-off intervals for a pool session. Enter a recent timed swim, then set a target distance to see your projected time.
The critical swim speed (CSS) section uses a 400 and a 200 time trial to estimate the fastest pace you can sustain for roughly 30 minutes, which is the basis of most threshold swim sets. Projected times assume an even pace; real races are usually a little slower over longer distances and faster over short ones.
With the default inputs, the pace per 100 is 2m. Change any value above to recalculate instantly.
How to use the swim pace calculator
- 1Choose metres or yards to match your pool or course.
- 2Enter the distance you swam and your time in hours, minutes and seconds.
- 3Set a target distance to project a race or workout finish time.
- 4Optionally enter 400 and 200 time-trial results in seconds to get your CSS pace.
- 5Use the split table to plan intervals and pacing for each distance.
Formula and method
Pace is total time in seconds divided by the distance, multiplied by 100 to express it per 100 metres or yards. Speed is distance divided by time; yards are converted to metres (1 yd = 0.9144 m) before showing m/s and km/h. Projected times simply multiply your pace by the new distance, so they assume you can hold an even pace.
Critical swim speed treats the difference between a 400 and a 200 time trial as the time it takes to swim an extra 200 at a sustainable effort: CSS = 200 ÷ (T400 − T200). It approximates your threshold pace and is used to set intervals for threshold and endurance sets.
- T400
- 400 m (or yd) time trial in seconds
- T200
- 200 m (or yd) time trial in seconds
- CSS
- Critical swim speed, distance per second
Worked examples
1500 m in 30:00
1,800 seconds for 1,500 m is 1.2 s per metre, or 2:00 per 100 m (0.83 m/s). At that pace a 1,900 m half-Ironman swim takes 38:00. The 6:00 / 2:50 time trials give a CSS of 200 ÷ 190 = 1.053 m/s, or 1:35 per 100 m.
1000 yd in 17:30, Ironman projection
1,050 seconds over 1,000 yards is 1:45 per 100 yd. 1,000 yd is 914.4 m, so speed is 0.871 m/s. The 2.4-mile Ironman swim (4,224 yd) at the same pace would take about 1:13:55.
Open-water 3.8 km in 1:10:00
4,200 seconds for 3,800 m is 1:50.5 per 100 m, or about 3.26 km/h. At that pace an Olympic-distance 1,500 m swim would take about 27:38. CSS is skipped because no 400 time was entered.
Frequently asked questions
What is a good swim pace per 100m?+
Many adult fitness swimmers hold around 2:00–2:30 per 100 m for steady freestyle, trained triathletes often swim 1:30–1:50, and competitive pool swimmers are faster still. Compare your pace with your own past results rather than others.
How do I test my critical swim speed?+
After a thorough warm-up, swim a maximal 400 time trial, recover fully (often 5–10 minutes easy), then swim a maximal 200. Enter both times in seconds; CSS = 200 ÷ (T400 − T200).
How do I convert pace per 100 yards to per 100 metres?+
Divide the yard pace by 0.9144. For example, 1:45 per 100 yd (105 s) equals about 1:54.8 per 100 m, because 100 m is roughly 109.4 yards.
Why is my open-water time slower than my pool pace?+
Pools give a push-off from the wall every length, which is free speed. In open water there are no walls, plus sighting, currents, waves and less precise courses, so most swimmers are several seconds per 100 slower.
How long does an Ironman swim take?+
The 3.8 km (2.4 mile) Ironman swim takes many age-groupers between about 1:00 and 1:30. At 2:00 per 100 m it takes 76 minutes; at 1:40 per 100 m it takes about 63 minutes.
This tool gives general estimates and is not medical advice. Talk to a doctor or qualified professional about your health, diet or training.